Neon tube



, l, May 10, 1927. R. R NACHI-ETT 628,256

NEON TUBE Filed oct.`1e. 192e.

INVENTOR @www 4MM" BWY EN z 42m.,

ATTORNEY -i-cury` is employed. Heretofore, in the manu- Y .facture of neon tubes, it lhas been assumed Patented May 10, 1927;

UNITED STATES lPnTlazwNT oFFIcE.

RAYMOND R. MACLETT, 0F NEW YORK, N. Y., ASSIGNOR TO RAINBOW LIGHT, INC., 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

NEON TUBE Application led October 16, 1926. Serial No. 142,026.

My invention relates to certain new andy useful improvements 1n neon tubes intended particularly for advertising purposes where the fiery orange color of the luminous'gas 1s f desirable. Particularly theinvention relates to neon tubes using interior electrodes to which an alternating current of high lvoltage is supplied, wherebythe conducting gaseous atmosphere of neon will be made luminous.

Usually, in the a pressure of about 8 millimeters of mer- 'that a satisfactory life can be secured only by the use'of gas of very great purity and by the employment of special methods by which gaseous'impurities can be eliminated from the tube, and 'by which occluded gases can be removed from the walls of the 'tube and the electrodes themselves.

It was ,the belief generally accepted by the art that the presence of foreign gaseous impurities, contaminating the neon atmosphere, shortened the life of the tube, and hence it was considered of vital importance that precaution should .be taken to prevent the presence or development of foreign gases in the' tube.

I have discovered. that the generation or presence of certain gases in a neon tube, are U lent results by the use of magnesium carbon-v not only undetrimental to the operation thereof but actually result in securing much greater length of life of the Atube than is possible if such foreign gases yare not employed. Specifically, I have found that if a diatomic gas, such as carbon monoxide gas is caused to slowly evolve in the operation of thetube so as to be localized in the immediate neighborhood of the electrodes, it is. possible to construct aneon tube having a lifeof from four to six or more thousand hours. Apparently, the foreign gas which is thus localized in the neighborhood of the electrodes, performs a beneficial function in connection with the transfer of energy from the metal electrodes to the neon gas.

The functioning of the foreign gas seems to be due tothe phenomenon of ionization. Its presence may be observed with a spectroscope. Preferably, I rovide for the slow evolution of the forelgn gas by charging each electrode with a suitable supply of a salt, which, in the operation .of the tube, Will become chemically dissociated, soV as Iformation of neon tubes eign gas will be generated and will find its way into the 'neon column between the electrodes, audit will injuriously effect the colorof the light as well'asJ the operationof the tube.

In order that my invention may be fully understood, attentionis directed to the accompanying drawing, which I illustrate a conventional form of neon tube equipped with electrodes in, which the desired lt may be carried. The body', l, of the tu e, is of suitable `diameter and length and is generally formed in the shape of a letter or symbol for'a'dvertisingpurposes.-v The ends of the tube are enlarged as at -2 so as toform chambers for receiving theelectrodes. The electrodes, 3, Vare made preferably of carbon and are carried on suitable conductors 4, ex-

tending lthrough the end walls of the tube.l

Each electrode is formed with a cylindrical bore or chamber 5, therein for receiving a charge 6, of the desired salt for the genera.- tion of the foreign gas.'y

In actual practice, I have achieved excelate, which upon dissociationv and because of conditions within the tube results inl the generation of carbon monoxide gas. Care should .bc taken that the gas Whichis thus generated Will'be localized in` the immediate neighborhood of the electrodes so as to fac-ilf of, as for .example sodium nitrite, which upon dissociation will result in the generation of nitrogen in the immediate neighborhood of the electrodesvand will` lalso act beneficially in prolonging the-,life of the tube. As amatter of fact, myobservation' is that generally any diatomie gas existing in limited quantities in the neighborhood of the electrodes will producethe. desired effect, and therefore it is only necessary that the material carried within the electrode shall have a sufliciently low vapor pressure so as to cause the foreign gas to be slowly evolved.

In order to determine whether the electrodes are of proper proportion with respect to current used, a spectroscopic examina,- tion of the tube. if made, should disclose the spectrum .of the foreign gas in the neighhorheozl of the electrodes and the'absence of the same spectrum in the conducting neon column. If such an examination discloses the spectrum of the foreign gas in the neon column. it indicates that the electrodes are too small or else that a salt has been chosen whos-,i` raporprcssure is not adequate for the purpose.

It will be understood that before the neon gas is introduced into the tube, a vacuum should be first produced therein by means of suitable vacuum creating appliances, with which the art is familiar, after which substantially pure neon gas is allowed to enter the tube to lill the same at a pressure of about 8 millimeters of mercury. If this pressure is substantially increased, the resistance of the tube will be vobjectionably affected. A lower pressure is not approved because it has been found that in operation the pressure of the neon in the tube slowly diminishes until a point is reached Where the tube becomes non-conducting. Therefore any initial reduction of pressure below 8 millimeters of mercury, results in shortening the life of the tube.

I find that it is desirable in pumping the tubes, to maintain a discharge between the electrodes resulting in the evolution of carbon monoxide gas therefrom, assuming that magnesium icarbonate is utilized as thegas producing salt. Gradually the tube becomes filled with carbon monoxide gas, which effect can be observed by means of a spectroscope and the current between the electrodes is continued until the spectroscope indicates the presence in the tube of an atmosphere of pure carbongas only, whereupon the passage of the current is discontinued, so that no further evolution of carbon monoxide takes place. The continued operation of the vacuum pump will remove such gas from the tube and result in the production of a vacuum therein which will be replaced, as stated, by the introduction of the neon.

The special treatment proposed above of generating from the electrodes the desired foreign gas in the tube until its formation and prior to the introduction of theneon, results in the elimination of hydrogen, water vapor and other contaminating influences which might tend to interfere with the correct operation of the tube. It is to .be particularly noted lthat no special precautions are required in the way of baking the tubes or over-heating the electrodes for the removal of occluded gas and as a matter of fact in the operation of my improved neon tube the desirable effect is based upon the fact that gases are continuously emanating from the electrodes.

It is not necessary in the carrying out of my invention, to make use of absolutely pure neon gas, and in fact, in practice I prefer to make use of so called neon-helium, spectralrein, in which the neon is associated' with helium (frequently 10%) the presence of which can be determined spectroscopically. It will therefore be understood that where reference is iliade to `neon in the appended claims I include such a mixture of neon and helium. lvhile I prefer to make use of neon as the source of illumination, owing to its brilliantly colored radiationand to its desirable tonducting properties, yet it will be understood that other nionatomic gases of the so-called noble group, may be employed, such as argon, krypton, Xenon or helium, all of which act the same as neon, except as to their distinctive spectra and in their conducting properties.

Having now described my invention, what I claim is new therein and desire to secure by patent, is as follows:

1. A luminous tube having a monatomic `gaseous conducting atmosphere therein and having interior electrodes and means within the tube for supplying al foreign gas localized in the immediate neighborhood of the electrodes for facilitating transfer of energy from each electrode to the conducting gas, as set forth.

2. A luminous tube containing a monatomic gaseous conducting atmosphere therein and having interior electrodes within the tube and means for supplying carbon monoxide gas localized in the immediate neighborhood of the electrodes for facilitating the transfer ot' energy from each electrode to the conducting atmospht-:avas set forth.

8. A luminous tube containing an atmosphere of neon therein, and having interior electrodes within the tube and means for supplying a foreigngas localized in the immediate neighborhood of the electrodes for facilitating transfer of energy from the electrodes to the neon atmosphere, as set forth.

4. A luminous tube /containing an atmosphere of neon, interior electrodes within the tube and meansfor supplying carbon monoxide gas localized in the immediate neighborhood of the electrodes for facilitating the transfer of energy from the electrodes to the neon atmosphere, as set forth.

5. A luminous tube containing a conducting monatomic gas, interior electrodes within the tube and means for supplying a diatomic vgas in the immediate neighborhood Aof the electrodes to facilitate transfer of energy l from theelectrodes to the conducting atmospherel as set forth.

6. A luminous tube containing neon, interior electrodes within the tube and means for supplying a diatomic gas localized in the immediate neighborhood of the electrodes to facilitate transfer of energy from the electrodes to the neon atmosphere, as set forth.

7. A luminous tube containing a monatomic conducting gas, interior electrodes within the tube and a salt carried by said eleitrodes which upon dissociation will furnish a supply of a foreign lgas localized in the' immediate neighborhood of the electrodes to facilitate the transfer of energy from said electrodes to the conducting atmosphere, as set forth.

8. A luminous tube containing a monatomic conducting as, interior electrodes within the tube an a. salt carried b said electrodes which upon dissociation w' -sup- `ply a diatomic gas localized in the immediate neighborhood of the electrodes to facilitate the transfer of energy therefrom to the conducting atmosphere, as set forth.

9. A luminous tube containing a monatomic conducting gas, interior electrodes within the tube, and a charge of magnesium carbonate in each electrode 'ada ted to be dissociated in the operation of t etube to generate carbon monoxide gas localized in the immediate neighborhood of the electrodesl to facilitate the transfer of energy therefrom to the conducting atmosphere, as set forth.

10. A luminous discharge tube having interior electrodes and containing a conducting atmosphere of a monatomic gas, said tube also containing in the neighborhood of the electrodes a localized body of a diatomic gas, as set forth RAYMOND R. MACHLETT. 

